Oswaldo Arcia's rookie season was filled with the expected peaks and valleys that most normal human rookies encounter during their first year of facing the world's best competition.
Offensively, he displayed flashes of unbridled power by depositing home runs to all fields but alternated those moments with stretches of being lost. Over three games in early July, Arcia woofed 11 times in 18 at-bats. In that small sampling, he swung the bat 26 times but managed to put the ball in play just three times (two infield flies and a medium fly to left) while missing 16 times and fouling off seven more.

Sent back to Rochester shortly thereafter – perhaps just for his own sanity's sake as he seemed ready to snap – Arcia returned to Minnesota in August for the duration of the season and continue to hit the ball hard (when he made contact).

Like many overzealous noobies, Arcia struggled to maintain respectable plate discipline figures that he worked hard to cultivate while in the minors in 2012. In the bigs, he reverted back to his previous ways and swung harder and more frequently than your parents at the neighbor's key party in the late 1980's.
There were pros and cons to this approach.
First, Arcia thrived in hitter's counts when he could anticipate the heater. Perhaps because he was an unproven player, the Twins outfielder saw a higher than average amount of fastballs when he had the drop on pitchers (70% vs. 62% league average) and he was able to capitalize. Of his 14 home runs, seven came on fastballs when he was ahead in the count. Beyond that, just based on batting average, he was baseball's best when ahead in the count – his .509 batting average led the game (minimum 50 plate appearances).
Skeptics can (rightly) point out that this is a small universe to make any sweeping proclamations however the takeaway is that in situations Arcia needed to take advantage and he did. The reason that Arcia's plate discipline numbers were so skewed towards the pitcher's favor is because, far too often, the pitcher was in the catbird seat. Under those circumstances, he struggled mightily and hit just .160 as pitcher's put away the fastball (just 44% of the time) and opened up their repertoire to twirl different offerings past his bat.
Visually, we can see how much better Arcia's swing zone is when he is ahead in the count compared to the vast swath of real estate he tries to cover once he falls behind. It turns into an "Oh my god, here's strike three coming: Kill it! Kill it!" mentality.
(via ESPN Stats & Info)
There is no question that Arcia's swing is fundamentally strong. With strong engagement with his lower half (controlled stride, solid hip involvement), his ability to keep his hands in to his body allows him to drive the ball well to all fields.

As Arcia develops his pitch recognition and comprehension skills, the presumption is that he will be behind in the count less often as pitchers become more reluctant to throw him anything cherry. If he is able to ignore those out-of-zone pitches, this should allow for him to jump on more of the suitable pitches and deploy his powerful swing.